Apparatus for gas borne powder distribution



Sept. 20, 1960 B. H. ACOMB APPARATUS FOR GAS some: POWDER DISTRIBUTIONFiled Sept. 4, 1956 INVENTOR. BYRON H. ACOMB ATTORNEY United StatesPatent APPARATUS FOR GAS BORNE POWDER DISTRIBUTION Byron H. Acomb,Watchung, N.J., assignor to Union Carbide Corporation, a corporation ofNew York Filed Sept. 4, 1956, Ser. No. 607,656

4 Claims. (Cl. 302-17) This invention relates to apparatus for gas bornepowder distribution employing pinch valves, and more particularlyemploying diaphragm operated valves of this character for turning on andoif the flow of powder-laden gas used, for example, in electric weldingand in the thermochemical removal or deposition of metal.

The main objects of the present invention are to provide apparatusemploying a valve of this character which can be operated by theconveying gas, thereby eliminating the necessity of a separate gassource, and to maintain a pressure difierential between the chamber andconveying tube so that the tube can withstand pressures in excess of thebursting limit of the material thereof.

Other objects are to provide apparatus employing a valve of thischaracter to turn on the flow of carrier gas before turning on the flowof powder, and for turning ofi the flow of powder While continuing theHow of carrier gas. According to the present invention, a stream of gasis passed along a first circumferentially confined path, powder isaspirated into said path to form a gas borne powder stream which ispassed along a flexibly confined further path. The stream of compressedgas is diverted from ahead of said aspiration step to a confined zonesurrounding said confined path, and the pressure of said divertedcompressed gas in said confined zone is utilized to pinch said flexiblyconfined path and cut off the flow of said gas borne powdertherethrough.

In the drawings:

Fig. 1 is a diagram or flow sheet for the method of powder distributionaccording to the present invention, showing the injector and by-pass,with the pinch valve open; and

Fig. 2 is a similar diagram with the pinch valve closed.

As shown in the drawing, a stream of compressed gas is passed along afirst circumferentially confined path 37. Powder is aspirated into thispath at 39 to form a gas borne powder stream. The gas borne powderstream is passed along a. flexibly circumferentially confined furtherpath 30. The stream of compressed gas is diverted at 36 from said firstpath 37 ahead of the aspiration step at 39 to a confined zone '10surrounding the flexibly confined path 30. The pressure of the divertedgas is utilized in the confined zone to pinch the path 30 and cut offthe flow of gas borne powder therethrough.

The body 10 is provided with a by-pass 35 for pressurizing the chamberunder the diaphragm 14 and surrounding the pinch tube 30. As shown inFigs. 1 and 2 the by-pass 35 is connected to a two-way valve 36,preferably solenoid operated. The valve 36 is connected to a supply line37, and through a check valve 38 and injector 39 to the pinch tube 30.

When the pinch valve is in its normally open position shown in Fig. 1,the loading of the spring 15 on the diaphragm 14 depresses the pinchingarm 22 so that the pinch tube 30 is wide open. The carrier gas from thesupply line 37 passes through the valve 36 and check valve 38 to theinjector 39 where it picks up the powder and carries it through the openpinch tube 30 for delivery and use.

2,953,411 Patented Sept. 20, 1960 "ice To close off the pinch valve 30,the valve 36 is turned to the position shown in Fig. 2. The carrier gasfrom the supply 37 passes through the valve 36 and 35 to the pinch valvechamber in the body 10. The gas pressure against the diaphragm 14 issufficient to overcome the loading of the spring 15 and the pinching armis raised, thus compressing the pinch tube 30 between the roller 25 andthe yoke 28.

What is claimed is:

1. Apparatus for gas borne powder distribution which comprises a supplyconduit for a stream of compressed gas, a two-way valve in said conduitoperable in one position for passing said stream through an injector toentrain powder therein, an outlet conduit from said injector for passingsaid gas borne powder stream through a pinch tube, a diaphragm havingmeans connected thereto for pinching said tube, a second conduit forminga bypass from said two-way valve to said diaphragm, said valve beingoperable in a second position for cutting ofl. said stream of compressedgas to prevent it going through said injector, but instead directing itthrough said second conduit to said diaphragm to cause said pinchingmeans connected thereto to pinch said tube and cut off the flow of saidgas borne powder.

2. Apparatus for gas borne powder distribution which comprises means forpassing carrier gas from a supply line to a powder injector to entrainpowder therein, means for passing the gas borne powder stream through apinch tube to a delivery line, means for by-passing carrier gas fromsaid supply line ahead of said injector to a pressure chamber, and meansfor pinching said tube in response to pressure in said chamber todecrease the flow in said gas borne powder delivery line.

3. Apparatus for gas-borne powder distribution which comprises means forpassing a non-powder laden stream of compressed gas from a supply linealong a predetermined path and through an injector to entrain powdertherein, means for passing the gas-borne powder stream from saidinjector through the tube of a diaphragm-operated pinch valve, means fordiscontinuing the flow of said non-powder laden compressed gas from saidsupply line to said injector at a point ahead of said injector beforesaid compressed gas can become powder entrained, means forsimultaneously diverting said stream of non-powder laden compressed gasfrom said supply line along a different path away from said injector,and means for recontinuing said stream of non-powder entrained gas fromsaid supply line along said difierent path and directing it to thediaphragm of said pinch valve to cut oil the flow of said gas-homepowder.

4. Apparatus for gas-bome powder distribution which comprises means forpassing carrier gas from a supply line to a powder injector to entrainpowder therein, means for passing said carrier gas from said injectorthrough a pinch tube to a delivery line, means for by-passing carriergas from one of said lines to a pressure chamber, and means for pinchingsaid tube in response to pressure in said chamber to decrease the flowin said delivery line.

References Cited in the file of this patent UNITED STATES PATENTS1,123,155 Woodley Dec. 29, 1914 1,223,586 Johnson Apr. 24, 19172,183,835 Foulke Dec. 19, 1939 2,588,212 Custer Mar. 4, 1952 2,590,215Sausa Mar. 25, 1952 2,590,396 Garretson Mar. 25, 1952 2,649,340 WeinrichAug. 18, 1953 2,816,803 Clark Dec. 17, 1957 FOREIGN PATENTS 208.801Switzerland 194g

